Metal fluoride coated lithium intercalation material and methods of making same and uses thereof

Abstract

Provided herein is a method of reducing the charge / discharge capacity fade rate of a rechargeable lithium-ion battery (LIB) during cycling, and extending the life and the number of discharge / recharge cycles thereof, effected by coating particles of lithium intercalation materials used for making the electrodes of the LIB, with a uniform layer of a metal fluoride effected by atomic layer deposition (ALD). Also provided are coated particulate lithium intercalation materials, electrodes and lithium-ion batteries having electrodes made with particulate lithium intercalation materials coated with a uniform later of a metal fluoride using ALD.

Description

FIELD AND BACKGROUND OF THE INVENTION[0001]The present invention, in some embodiments thereof, relates to electrochemistry, and more particularly, but not exclusively, to a modified particulate lithium intercalation electrode material and a method of reducing a capacity fade rate during discharge / recharge cycling of a lithium-ion rechargeable battery.[0002]In the 1970s-1980s, the concept of a Li-ion secondary battery (rechargeable cell) has been demonstrated based on the substitution of a Li metal anode with Li-ion intercalation compounds. The rudimentary cell consists of an anode, a cathode, an electrolyte and a separator, wherein lithium ions reversibly intercalate and de-intercalate into / from the anode and cathode materials on operation (discharge / recharge cycles). The materials consist of a host material with Li+ ions accessible to inter-atomic sites. Lithium ion intercalation / de-intercalation causes a change in the charge distribution inside the host material skeleton and an ov...

AI Technical Summary

Benefits of technology

The present invention provides a method for improving the stability and effectiveness of a metal fluoride layer on the surface of particles used in the formation of a rechargeable lithium-ion battery electrode. The method involves heating the metal fluoride layer to relatively high temperatures, which can make it more stable and effective against charge / discharge capacity fade of the battery. The method can be carried out using known metal sources or fluoride sources for atomic layer deposition. By coating the particulate lithium intercalation material with a uniform layer of metal fluoride, a rechargeable lithium-ion battery electrode with improved stability and performance can be obtained.

Problems solved by technology

Whereas lithium mobility in the carbon anode is sufficiently high, the development of cathode materials with substantial Li+ mobility turned out to be an issue of prime importance.

This cathode material dissolution compromises the cathode electrical conductivity and leads to the battery capacity losses; as the result, the promising spinel-type materials suffer from an impractically short lifetime in terms of discharge / recharge cycle number.

Furthermore, while spinel-type material based lithium ion batteries typically have good performance at room temperature, these batteries suffer a gradual loss of delivered capacity with cycle number at elevated temperatures, referred to as capacity fade or the capacity fade rate.

Such metal oxides may be used as Mn+3 barriers, however these oxides suffer from limited resistance against hydrofluoric acid attack, especially at elevated temperatures.

In addition, most of the metal oxides, which have low Mn+3 permeability, also exhibit poor Li+ permeability [e.g., U.S. Pat. No. 9,012,096; Jung, E. et al., J. Electroceram., 2012, 29, p.

However, metal oxides are prone to hydrofluoric acid attack and promptly degrade with discharge / recharge cycling, while increasing the coating's thickness enhances the coating stability but compromises Li+-diffusivity.

However, wet chemistry-based metal fluoride deposition processes afford non-uniform and / or porous coatings [Bernsmeier, D. et al., ACS Appl. Mater. Interfaces, 2014, 6:19559-19565], which lead to low protective features and / or low Li+ permeability.

Although some battery lifetime improvements were reported, it has been shown that in some areas the protective film failed to prevent Mn+3 passage while another areas of the same coated sample exhibited too high resistance for Li+ permeability; evidently, such performance compromises cathode cycle life.

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